The Ohio Star is a nine patch block and uses quarter square triangles in its construction.
The basic star has only the edge squares of the nine patch grid replaced with quarter square triangles- clever use of colour gives a square within a square illusion.
Here is a video with this basic variation
You can also replace the corner squares to give a more complex variation as shown here
When the corner squares are replaced with four patches it is sometimes called the Ohio Trail
Here are written instructions for the basic variation from chock-a-block for a 12 inch finished size.
This version is from Generations Quilt Ohio Star Quilt Block: 3", 4-1/2", 6", 7-1/2", 9", 12" blocks
Scissortail Quilting includes example quilt layouts
The Square and Half Square block uses an Ohio Star in the centre and then builds out
Patchwork Square has instructions (click on block) plus example quilt layouts
This example is from Generations Quilt Variable Star Quilt Block: 6", 7-1/2", 9", 12" and 15"
FavCrafts used this block as part of a sampler quilt